On Wednesday, May 4, Paul Graham is giving a talk at PARC in Palo Alto:

Most people who start startups do it to get rich, and the most common way to get rich from a startup is to sell it. Investors call this an "exit strategy," and they won't even consider a company that doesn't have a fairly clear one. In this case the founders and investors' interests are aligned: you should be thinking about exit strategies before you even start a company. In this talk I'll describe the kinds of ideas that yield buyable startups, the different stages at which you can sell a startup, and what you should do (and not do) to make it happen at each stage.

There are two basic ways of raising money for your business. By selling equity, or stock, in your company, or like coo+dle says, borrowing money at a set interest rate. When people talk about startup funding they usually mean the former in the form of venture capital. Debt, of course, also has an "exit strategy" which is you have to pay back the principal with interest. It's pretty unreasonable to expect someone to give you money for a while without any idea of how they're going to get it back. And if you do sell the company, you don't have to sell your share! That's the fun of dividing ownership up into tiny little pieces.